The present invention generally relates to the processing of fish and particularly to the removal of skin or scale from fish such as tuna.
The processing of tuna entails taking tuna from the vessels to a tuna processing plant where the fish are initially beheaded, eviscerated, and then placed in containers for precooking. The precooking operation generally takes place in steam ovens or chambers as described in U.S. Pat. No. 3,594,196. Steam is used to precook the raw fish and precooking is carried out for a period of time that is between 0.5 and 10 hours depending upon the size of the fish being processed. After precooking, the fish are then allowed to cool at which time they are taken from the container in which they are cooked and placed on trimming tables where workers will manually remove the skin, bones and other portions of the fish considered unsuitable for human consumption. Skin or scale removal from the fish is a major step in the fish processing operation since it entails the use of manual labor to remove the skin from the fish and entails a considerable amount of time and skill. For example, the skin must typically be stripped by hand in which a knife is used as an assisting means in order to completely remove the skin from the fish. Therefore, a means of assisting in removal of the skin from tuna would represent a significant improvement in the processing of fish or tuna and provide a considerable savings in the costs of producing these products.
U.S. Pat. No. 3,806,616 describes a process for the skinning of fish in which a caustic solution is applied to the skin of the fish to saponify the fat therein and cause a partial dissolving of the skin after which the skin can be brushed or washed away. This type of procedure, however, involves the use of caustic and corrosive chemicals which can be harmful for a worker to handle and might also adversely effect the quality of the fish meat.
It would therefore be highly desirable if a means could be found for the skin removal from fish, such as tuna, which was simple and reliable to practice on a commercial scale and did not involve the use of chemicals not suitable for food usage or which are difficult to handle in a commercial operation.